As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AIRCRAFT WAS AT ALTITTUDE, FLIGHT CREW RECEIVED WARNING NR 2 ENGINE YELLOW HYDRAULIC SYSTEM PUMP HAS LOW PRESSURE. DECLARED EMERGENCY, AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. REPLACED THE O-RING AT POWER TRANSFER UNIT REDUCER IAW AMM 29-13-15. AIRCRAFT WAS GROUNDED.